1. Field of the Invention
The present invention relates to a temperature measuring device that utilizes an infrared temperature sensor that measures temperature, for instance, a temperature measuring device used for measurement of exhaust air temperature of an internal combustion engine.
2. Description of the Related Art
So-called exhaust temperature sensors are conventionally known in which the temperature of exhaust gas flowing through an exhaust gas passage such as an exhaust pipe of the interior of a catalytic converter of a purification device in an automobile, is detected by a thermistor element being a temperature sensing element.
In a temperature sensor of this kind, a thermistor element is provided at the tip of a wiring member for extracting signals to the exterior, the tip portion being covered with a metal case having a bottomed tubular shape. The thermistor element is accommodated within the space formed by the metal case and the tip portion of the wiring member.
Further, the interior of an outer tube made of metal is packed with an insulating powder, between the outer tube and core wires, as a result of which the core wires are held insulated from the outer tube. A coupler for electrical connection to the exterior is provided, in a pair of lead wires, at a portion on the end of the lead wires opposite that of a connection portion with the core wires.
In temperature detection by such a temperature sensor, exhaust gas heat from exhaust gas is received by the metal case, and is thereafter transferred from the metal case to the thermistor element (for instance, Japanese Patent Application Publication No. 2000-171308).
As a further temperature detection method, so-called infrared temperature measuring devices are also known in which temperature is detected by an infrared temperature detection unit, being a temperature sensing element, in a state where the detection unit is spaced from a heat source. In a temperature measuring device of this type temperature is detected by detection of infrared light from a temperature sensing part, in the form of the tip section of a tubular member, by an infrared sensor element being a temperature sensing element that is disposed spaced from the temperature sensing part.
In such an infrared temperature measuring device the temperature sensing part is disposed spaced from an infrared temperature detection means, and it is the tubular member that is disposed directly within the high-temperature exhaust gas. Accordingly, it becomes possible to avoid exposure of the infrared temperature detection unit to the high-temperature exhaust gas, and to suppress thermal degradation of the infrared temperature detection unit. Further, the temperature sensing part can be formed having a thin wall. A fast thermal response can be achieved as a result (for instance, Japanese Patent No. 5828033).
As a further temperature detection method, systems are known where, in an internal EGR control device of an internal combustion engine, a target internal EGR amount is corrected in accordance with the temperature of exhaust gas as detected by an exhaust temperature sensor and the pressure of exhaust gas as detected by an exhaust pressure sensor, the sensors being disposed inside an exhaust pipe.
The internal EGR control device controls an intake-exhaust valve timing varying mechanism and a lift mechanism, and controls an internal EGR amount by modification of a degree of valve overlap between an intake valve and an exhaust valve.
Further, the internal EGR control device corrects the targeted internal EGR amount in accordance with the temperature and pressure of the exhaust gas. The internal EGR control device allows controlling more properly the internal EGR amount, by compensating thus control errors derived from changes in temperature and pressure (for instance, Japanese Patent No. 4583354).